An electronic cigarette, through heating and further atomizing its liquid smoke, is provided to smokers as a succedaneum of cigarette; and the electronic cigarette becomes more and more popular for smokers. At present, when users use electronic cigarettes, many users find that the taste of electronic cigarettes is changed. The cause is the electronic cigarettes are stored over their expiration date and the taste is becoming worse. Currently the production date and expiration date of the electronic cigarettes are only marked on their product packages or products, which make it harder to detect by user. When the electronic cigarettes being past their expiration date are inhaled, users can feel bad taste and the users' healthy may be affected.